Difference between 12-bit address and 12-bit address operand?

This is a discussion on Difference between 12-bit address and 12-bit address operand? within the Tech Board forums, part of the Community Boards category; Hello,
I have an exam coming up tomorrow and I was wondering if someone can help me understand the difference ...

It's possible that an instruction cannot take the same number of bits as an address as the native width of addresses on the architecture.

For example, on some 8-bit microcontrollers with 16-bit addresses (like the Intel 8051), most instructions only take 8-bit addresses. To access the rest of the memory space, you need to use a special instruction to move data into the 8-bit address space first.